Making popcorn gives you a good idea of how heat bursts the starch wall. Puffed cereals are made in a similar way.
Things Required:
About 1/2 cup of popcorn kernels
1/4 cup of vegetable oil
A deep, heavy saucepan with a wooden handle and a cover
Directions:
Heat the pan on high heat for one or two minutes, and then pour in enough oil to cover the bottom of it. Lower the heat to medium. Add a few kernels and cover the pot. When you hear those kernels start to pop, add just enough popcorn to cover the bottom of pot. Lower the heat. Put on the lid.
Shake the pot from time to time, but don’t remove the lid while you can hear crackling sounds. When the sounds stop-within a minute or two-remove the pot from the stovetop and uncover it.
This Is What Happens:
You have a mountain of popped corn!
Science Behind It:
The moist and pulpy heart of the corn kernel is surrounded by a hard starch shell. When the kernel is heated, the moisture in the kernel turns to steam; the heart gets bigger and the shell bursts.
The grains of starch behave a lot like the kernels of corn. When heat breaks the wall, the starch comes out and mixes with water. It is then in a form that we can digest.
All recipes that have flour as an ingredient-cake, biscuits, bread, gravies, sauces, puddings-must be cooked so that the starch in the flour may be released.
